This invention relates to a tape carrier and, more particularly, to a tape carrier for use in a molded Tape Carrier Package (T.C.P.) structure. This invention also relates to a semiconductor device on the tape carrier and a method of making the same.
FIG. 5 is a sectional view illustrating a known tape carrier for use in a T.C.P. In FIG. 5, a tape carrier 5 comprises a carrier tape 1 made, for example, of polyimide, leads 2 disposed on the top surface of the carrier tape 1 and testing pads 3 disposed on the top surface of the carrier tape 1 and electrically connected to one end of each of the leads 2 for use in testing. A resist 4 is disposed on the carrier tape 1 as well as on the lead 2.
FIG. 6 is a top plan view of a known semiconductor device using the known tape carrier 5 illustrated in FIG. 5 but with the resin removed for clarity. As illustrated in FIG. 6, a plurality of the leads 2 are electrically connected at one end to the testing pads 3 and electrically connected at the other end to a semiconductor chip 6 and extend outwardly from each side of the semiconductor chip 6. Perforations 18 along both sides of the carrier tape 1 are at fixed intervals along straight lines. During manufacture and test, the carrier tape 1 is fed and held in place by a sproket wheel (not shown) engaging the perforations 18.
The testing pads 3 are disposed close to the perforations 18 so that the testing pads 3 can be touched easily with, for example, a testing pin (not shown) during testing. Since the testing pads 3 have a width such as 0.7 mm which is wide as compared with that of the leads 2 and the testing pads 3 are disposed at very minute intervals such as about a few hundred .mu.m, it has been recently difficult to increase the number of the testing pads 3 with an increase in the number of the leads 2. Further, as seen from FIG. 6, a hole 8 is disposed in the carrier tape 1 through which molten resin flows on the top side of the carrier tape 1 from the underside thereof when the semiconductor chip 6 is being molded together with the tape carrier 5 in a metal die.
FIG. 7 is a sectional view taken along line 7--7 in FIG. 6 and illustrates one example of a known molding method. As seen from FIG. 7, the semiconductor chip 6 is mounted on a heat radiating metal cap 9. The semiconductor chip 6 is electrically connected to the leads 2 and the testing pads 3 through a bump 7 which is disposed on the semiconductor chip 6. The heat radiating metal cap 9 is a substantially dish-shaped member having a circumferential brim 9a at its edge which is attached to the bottom surface of the carrier tape 1 and an inside bottom to which the semiconductor chip 6 is attached. The tape carrier 5 and the semiconductor chip 6 as described above are clamped between mold dies for molding together with the heat radiating metal cap 9. The mold dies are composed of an upper die 10 and a lower die 11 which form a cavity 14 therebetween for accommodating the semiconductor chip 6, the tape carrier 5 and the heat radiating metal cap 9. Further, a first resin-supply runner 12 is provided in the lower die 11 to let the molten resin flow therethrough and a second resin-supply runner 13 is disposed in the upper die 10 which is connected to the first resin-supply runner 12 through the hole 8 in the carrier tape 1. The first runner 12 is placed at the position illustrated by a phantom line in FIG. 6. As illustrated in FIG. 7, disposed between the second runner 13 and the cavity 14 is a gate 15 through which the molten resin 16 flows into the cavity 14 from the second runner 13.
If the mold resin 16, which is attached to the testing pads 3 and the leads 2 which are disposed on the carrier tape 1 during molding, is cured and fixed on the testing pads 3 and the leads 2, the testing pads 3 and the leads 2 may be peeled off from the carrier tape 1 together with the resin 16 during the gate-breaking process for removing the runners 12 and 13. Accordingly, in order to prevent the molten resin 16 from attaching to the testing pads 3 and the leads 2, the molten resin 16 may be caused to flow under the carrier tape 1 through the first runner 12 disposed in the lower die 11 and is injected into the cavity 14 in a manner known as the low pressure transfer molding method. However, as the molten resin 16 cannot be directly injected into the cavity 14 from the first runner 12 disposed under the carrier tape 1 because of the heat radiating metal cap 9, the hole 8 must be disposed in the carrier tape 1 upstream of the cavity 14 so that the molten resin 16 flows from the underside of the carrier tape 1 to the top side thereof through the hole 8 and injected into the cavity 14 through the gate 15.
If there is a portion 14a defined outside of the heat radiating metal cap 9 within the cavity 14 and in which the mold resin 16 cannot be easily injected, a communication hole 9b may be disposed in the heat radiating metal cap 9. In the gate-breaking process for removing the resin 16 within the runners 12 and 13, firstly, the resin 16 within the gate 15 is snapped off by bending the carrier tape 1. Since the resin 16 within the first runner 12 is connected to the resin within the second runner 13 through the hole 8, the resin 16 within the second runner 13 is taken out from there through the hole 8 as the carrier tape 1 is being flexed. FIG. 8 illustrates a conventional semiconductor device of the T.C.P. structure manufactured by the above-described method.
In the known molding process as described above, the carrier tape 1 is clamped between the upper die 10 and the lower die 11. However, the carrier tape 1 cannot be clamped around the hole 8 as illustrated in FIG. 9 since the second runner 12 is formed within the lower die 11. Therefore, these unclamped portions of the carrier tape 1 expand and sag loosely due to heat of the mold dies 10 and 11 and an undesirable gap 17 arises between the carrier tape 1 and the upper die 10 as well between the carrier tape 1 and the lower die 11. When the molten resin 16 is led from the first runner 12 to the second runner 13 through the communication hole 8, the molten resin 16 undesirably enters into the gap 17. After molding, the cured mold resin 16 within the gap 17 remains attached to the leads 2 and the testing pads 3 as undesirable burrs 19 illustrated in FIG. 8.
Further, in the known semiconductor device, since the first and second runners 12 and 13, which are respectively disposed on the upper side and the underside of the carrier tape 1 and connected to each other through the communication hole 8 disposed in the carrier tape 1, must be provided in the metal dies 10 and 11, the structures of the metal dies 10 and 11 are not simple and the gate-breaking process is not easy and not efficient.
Still further, the undesirable burrs 19 hinder the removal of the unnecessary mold resin 16 within the runners 12 and 13 during the gate-breaking process and the unnecessary resin 16 as well as the burrs 19 cannot be easily removed, resulting in a poor appearance and a poor formability.